A team of researchers, led by the University of Minnesota, have discovered a new nano-scale thin film material with the highest-ever conductivity in its class. Credit: University of MinnesotaA nano-scale thin film material exhibits both the highest conductivity in its class and a wide bandgap, which makes it optically transparent. The combination of high conductivity and a wide bandgap make this film unique, since these characteristics do not usually co-occur.

These unique qualities could lead to improvements in electronic devices and more efficient solar cells.

“The high conductivity and wide bandgap make this an ideal material for making optically transparent conducting films which could be used in a wide variety of electronic devices, including high-power electronics, electronic displays, touch screens and even solar cells in which light needs to pass through the device,” said Bharat Jalan, a University of Minnesota chemical engineering and materials science professor and the lead researcher on the study.

Jalan’s research team developed the new material in response to the increasing price of indium, which is a common constituent of current display technology. The unconventional approach they adopted resulted in the promising new compound.

Typical thin-film compounds use an indium tin oxide. The Minnesota team instead grew a BaSnO₃ (barium stannate) thin film, replacing the elemental tin (Sn) with a chemical precursor of tin. Using the precursor increased reactivity and improved the metal oxide formation process. Barium and tin cost significantly less than indium; both are easily available.

Jalan and his colleague, graduate student Abhinav Prakas, discovered that their new process enabled them to control the thickness, composition, and defect concentration of the new film. They also found the material to be structurally superior.

The new process is reproducible and scalable, making it suitable for development for industrial processes. The team’s next step is to reduce defect concentrations.